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Thursday, June 24, 2010

Guestpost: Marcelo Gleiser

[A month ago, I was at a workshop at Perimeter Institute and I reported on a talk by Marcelo Gleiser. Marcelo's talk was very interesting and thought-stimulating. It touched upon very many different topics, from the process of knowledge discovery to the question of whether we should be searching for a fundamental theory of everything. In my post I expressed my opinion that of course believing in a theory of everything, if you take the name literally, is religion not science because if we had one we would never know if not one day we'd discover something that the theory would not explain. But the whole question of whether it exists is somewhat besides the point, the actual question (for me, the pragmatist) is what is a promising approach to take that will lead to progress.

My latest book, A Tear at the Edge of Creation, came out in the US early April. In it, I present a critique of some deeply ingrained ideas in physics. In particular, I examine the question of unification and the search for a theory of everything, arriving at conclusions that—judging from some of the reactions I’ve been getting in lectures and in various blogs around the world—are shocking to many people.

Of course, I welcome criticism and skepticism. We are used to this in scientific debates. What’s surprising to me, and perhaps alarming, is the speed with which superficial commentary in the blogosphere quickly escalates into complete misunderstanding of what it is that I am saying and why. So, I think the time is ripe for sketching a reply, even though the space here won’t do justice to the details of the argument. I do hope, however, that this will at least inspire critics and skeptics to actually read the book and judge for themselves and not through a few lines on a blog post.

Among other things, in the book I suggest that the notion of a final theory, that is, a theory that encompasses complete knowledge of how matter particles interact with one another, is impossible. First, note that “final theory” here deals only with fundamental particle physics. Any claim that physical theories could be complete in the sense of describing (and predicting) all natural phenomena, including why you’re reading this, shouldn’t be taken seriously.

First, we must consider if a complete theory of matter does exist. Second, assuming it does, if we can ever get to it. The first question is quite nebulous. We have no way of knowing if such a complete theory exists. We don’t even know what a “complete” theory is. You may believe it does and spend your life searching for it. That’s a personal choice. Or, like most physicists, you may believe this is nonsense, more metaphysics than physics. The second question, though, is tangible. Can humans achieve complete knowledge of the subatomic world?

To answer this question, we must look at how science actually works. In a post at her blog Back Reaction, physicist Sabine Hossenfelder expressed her surprise at my statement that it took me 15 years to figure out that the notion of a final theory is faulty. Sorry Sabine, I guess old habits are hard to break. At least, I did see the light in the end. Happily, she agreed with my basic argument, that since what we know of the world depends on our measurements of the world, we can never be sure that we arrived at a final explanation: as tools advance, there is always room for new discoveries. Knowledge is limited by discovery.

I go on to describe how the unifications that we have achieved so far, beautiful and enlightening as they are, are approximations and not “perfect” in any sense. The electroweak theory, a unification of the electromagnetic and the weak nuclear forces, is not a true unification but a mixing of the two interactions. Even electromagnetism, the paradigm of unification, only works flawlessly in the absence of sources. To be a truly perfect unification, objects called magnetic monopoles would have to exist. And even though they could still be found, their properties are clearly very different from the ubiquitous electric monopoles, e.g. point-like particles like electrons. We have partial unifications and we should keep on looking for more of them. This is the job of theoretical physicists. The mistake is made when symmetry, a very useful tool in physics, is taken as dogma.

I don’t agree with Sabine when she says that it doesn’t matter what you believe in as long as the search “helps you in your research.” I think beliefs are very important, and to a large extent drive what it is that we are searching and the cultural context in which research is undertaken. Wrong beliefs can have very negative consequences. And can keep us blind for a long time.

So, one of the points I make is that science is a construction that evolves in time to expand our body of knowledge through a combination of intuition and experimental consensus. There is no end point to it, no final truth to arrive at.

Now, here are some of the things that have been said about my arguments:

“Marcelo is disillusioned with unification; he has closed up his mind to string theory; he couldn’t find a Theory of Everything and now thinks no one can find one as well; he’s just frustrated; he doesn’t understand the role of symmetry in physics (!); he’s timing is bad because the LHC will be revealing new physics.” George Musser, at a Scientific American blog post wrote “My own reaction was that although it’s useful to caution against clinging to preconceived ideas about a final theory, Gleiser was too insistent on seeing the glass of physics as half-empty.” Musser goes on to say how much we do know about Nature and how much of that is due to the fact that simple laws govern natural phenomena.

It’s true that Musser (and Sabine) were basing their comments on a lecture I gave recently at the Perimeter Institute and not on my book (you can watch the video here). Even so, as I tried to make clear in my text, I would never put down the remarkable achievements of science and much less be foolish to say that there are no patterns and symmetries in Nature! After all, that is how science works, by searching for simplifying explanation of natural phenomena. Having the LHC turned on and able to probe physics at energies higher than ever before is a very exciting prospect.

If anything, my book is a celebration of the human mind and all that we have achieved in such a short time. The fact that I point out that science has limitations doesn’t detract from all of its achievements. Or from all that lies ahead.

I’m not disillusioned for not having found a TOE or for believing it doesn’t exist. I’m actually relieved!

The reactions that I have encountered only reinforce my point, that there is great confusion these days about the cultural role of science and scientists. Science is not a new form of religion, scientists are not holy men and women, and we don’t have or can have all the answers.

As I wrote in Tear at the Edge of Creation, “Human understanding of the world is forever a work in progress. That we have learned so much, speaks well of our creativity. That we want to know more, speaks well of our drive. That we think we can know all, speaks only of our folly.”

Hopefully, this acceptance of our perennial ignorance won’t be interpreted as an opening to religion and supernatural explanations. Let me make my position clear: behind our ignorance there is only the science we still don’t know.

38 comments:

I'm not sure it's worth expending so much effort in arguing this particular topic. If by some definitions a "theory of everything" is a theory that's successful in accounting for every technologically accessible phenomena we are currently able to measure and by other people's definition it's a final theory that governs everything at all energy scales above and beyond what we could ever hope to verify, it doesn't change the fact that work needs to be done in the direction of pursuing a more fundamental theory. There are still things that need explaining in fundamental physics, and while that's the case arguing about the end goal seems to be a matter of syntax over semantics.

It's a bit like political scientists debating about whether ending war and poverty on earth is ever possible, even in principle. It doesn't matter! We should always be trying to achieve peace and prosperity regardless of academic debates as to what we can realistically achieve.

p.s. I realise you're not saying we should stop looking, I guess I'm just echoing Sabine's point that it doesn't matter as long as it helps you in your research. I guess what I disagree with is that "beliefs are very important" and affect the cultural context of research. That's true in general, I just don't think so in this particular case, where it seems to be a choice between reaching for the impossible or the impossibly possible.

But I haven't read your book yet where I'm sure you make a convincing case, so will keep an open mind ;)

/*..a theory that encompasses complete knowledge of how matter particles interact with one another, is impossible..*/

IMO existing theories can be reconciled at least two dual ways. We can simulate behaviour of nested fluctuations of very dense particle gas, which are having character of nested dynamic foam. More formal but roughly equivalent approach can be the solving of ordinary wave equation in high number of dimensions. After then the 3D slices of such solution will be AdS/CFT dual if they will be separated by sufficient number of dimensions.

Sorry, I haven't read the book either, but maybe someone here can convince me that I should.

What’s surprising to me, and perhaps alarming, is the speed with which superficial commentary in the blogosphere quickly escalates into complete misunderstanding of what it is that I am saying and why.

News spread exponentially with polynomial decrease of understanding, blogs only accelerate the process.Unfortunatly, this is a fact we will have to live with :-)

I suggest that the notion of a final theory, that is, a theory that encompasses complete knowledge of how matter particles interact with one another, is impossible.

Taken at face value this is so obvious, that many people may have had the impression that you mean something else.

A little anecdote: A very gifted child had to pass a test to be admitted to school and was asked how many days a week has. It answered: 168. Why? It thought that no one would ever ask the silly question of how many days there are, and that the intended question was about how manyhours a week has.

Back to the topic:I'm told that professor Glaser was a string theorist, and now proposes that there cannot be a TOC.Of course I think that he means that there cannot be a reconciliation of QFT and GR in principle,and that it cannot be achieved through string theory in particular.

There is great confusion these days about the cultural role of science and scientists.

There is? I would like to know more about this, is it explained in more detail in the book?

In my opinion It's not a matter of being disillusioned or relieved in finding the TOE, but it's more a matter of curiosity for explanations.

Science has not to be a new form of religion, but affirming that we don’t have or can have all the answers is not still surely provable, it's only a personal metaphysics. So it is the statement “Human understanding of the world is forever a work in progress. That we have learned so much, speaks well of our creativity. That we want to know more, speaks well of our drive. That we think we can know all, speaks only of our folly.”. It's a personal metaphysics not THE TOE, the ultimate metaphysics, considering not the religious meaning that the term assumed in the last times but the philosophical ancient one: Metaphysics as the ultimate scientific explanation of the Physiscs, The Physics of the Physics, with no myths allowed in all of this process. It seems like some scientist have fear of breaking a taboo and leave the monopoly of the metaphyisical explanations to the religions. I hope this will change soon.

There seems to be great concern today among many scientists that lays at the heart of your argument and that is science should not be confused with being a religion. I would agree that the two should not be confused and yet point out that what they have in common is each are philosophies. The central differences being religion demands faith, which permits no doubt, while science demands it always be maintained, with the other difference being with religion reality is considered as a construct of reason, while in science this is only taken as far as to be firmly convinced that reality is a construct that can be defined by reason.

With the establishment of these differences is what has me confused with your position, for it is either to insist that some aspect of reality is not able to be reasoned or that we are doomed to be restricted to not attaining the level of reason that is required to have it discovered. As neither position can be supported by evidence I find it more consistent with that of the philosophy of religion than that of science. I think what is being confused here is that the function of doubt within science is to prevent us from closing our minds to reason as to permit discovery, rather than have it serve as a limit of such. I would then agree with some of your peers that your position is too pessimistic as resultant of confusing the utility of doubt, for believing instead it being a limit of the philosophy in general.

Let me make my position clear: behind our ignorance there is only the science we still don’t know.

There is nothing behind our ignorance except ignorance itself. Ignorance itself is defined as things we do not know, therefore I am calling you out on being tautological.

You are right though that science as religion is foolish. Atheists (that is to say: most Scientists, right?) will tell you it's because they regard religion in general as foolishness. They should know I suppose, as the militant ones are hardcore extremists in their faith and devotion to Atheism. Extremism plus a wee bit of blarney equals converts equals convert's money equals a brand new Porsche.

I for one have no problem with this subject being discussed, as long as we don't quit our day jobs. I've yet to see an ad in any paper for Philosophers or Metaphysicists, more's the pity.

No TOE is a distinct possibility. At the other end is the possibility that not only is there a TOE, but an infinite number, one for each and every point (or spacetime nugget if you're into LQG) of spacetime, that varies so little from point to point or galactic filament to galactic filament that we'd have to enter Alan Guth's brain and Inflation theory to notice a difference.

Back to practical reality: Any progress toward a GUT recently? Or did Glashow et. al. prove QFT isn't the way to achieve one? And what are Alain Connes and crew up to?

Frankly I didn't see any substance in the original Marcelo post about it and I don't see any in his reply.

OK, so he was searching for a TOE and now he convinced himself that it doesn't exist. That's great but why should anyone else care? Why spin it into some profound insight when he has no coherent arguments to offer to back his position? Is writing popular science books so profitable?

And for the record I do believe string theory is a dead end that symmetries won't get us any further but that certainly doesn't mean a TOE is impossible. There are so many tantalizing clues scattered around physics that I am almost certain there is a simple theory unifying all interactions waiting to be discovered. Unfortunately to get to it one has to cut his way through a jungle of epicycles.

Zephir: "More interesting question may be, whether scientists are really interested about TOE, if they would risk the lost of jobs, social prestige, etc by it.

My very private feeling supported by five years of personal experience with spreading of such theory is, they're not."

Zephir you don't have any theory just a random and incoherent mix of words and ideas. Instead of polluting internet with it use your "theory" to calculate one or more parameters of the SM from first principles, then every physicist will become very interested. This is a minimum requirement for any TOE so if AWT can't meet it no one will bother with it no matter how brilliant you think it is.

If there existed a theory of everything that was made of a finite set of axioms that was capable of formulating standard mathematics, then there would be statements in that theory which are undecidable. In particular there would exist sequences of integers which are unthinkable, and uncomputable. From which, by taking arbitrary digit expansions for any point in space-time, one would conclude that every point in space-time cannot be observed.

Grant funding, as professional business management, supports zero-risk ventures. Research outside accepted theory is disdained. Change can only arrive external to physics' illusions of knowledge.

"Gleiser was too insistent on seeing the glass of physics as half-empty." If it is a Klein bottle, it can be simultaneously full and completely empty. It's all in the symmetries. Choose poorly and obtain good approximations that are wrong answers.

Tevong wrote: "There are still things that need explaining in fundamental physics, and while that's the case arguing about the end goal seems to be a matter of syntax over semantics."

Well, I disagree that it's a matter of semantics. It's a matter of worldview. Newton, Einstein, Wigner and many others knew that our knowledge of the world is incomplete and imperfect. To promote the opposite is a statement of what humans are capable of. We need to go back to their humbleness.

Tim van Beek wrote: "Taken at face value this is so obvious, that many people may have had the impression that you mean something else."

I do. I'm interested in the question of knowledge and how it relates to the way we do science. I'm not sure I can "convince" you to read the book, but I can assure you it's not obvious or superficial.

Also, I'm not saying GR and QFT are incompatible in principle. We don't know the answer to this question and must keep trying to answer it. As for the science as religion comment, have you watched "What the Bleep do we know"? This kind of junk is all over the world, using pseudo science as new age religion.

Hi Phil,I'm really writing about how science attains knowledge of reality, what kind of culture it reflects. To say that science has limits, that we can't know all of reality is not pessimistic; it's just a consequence of how we acquire knowledge of the world.

Steve Colyer wrote: "There is nothing behind our ignorance except ignorance itself. Ignorance itself is defined as things we do not know, therefore I am calling you out on being tautological."

I'm not sure I get this. It's not a game with words, it's about what people think it's "out there". There's no tautology at all!

tpin wrote: "OK, so he was searching for a TOE and now he convinced himself that it doesn't exist. That's great but why should anyone else care? Why spin it into some profound insight when he has no coherent arguments to offer to back his position? Is writing popular science books so profitable?"

Discounting the gratuitous nastiness of your comment, I guess you will have to spend time reading the book to see if my arguments are just for profit or if there's something there. Also, you seem to contradict yourself, saying that symmetries are a dead end but a TOE may still be possible. Given the framework of theoretical physics, how would that work, exactly?

What we have is total lack of experimental evidence for a unification at higher energies: no proton decay, no monopoles, no SUSY particles, in spite of 35 years of searches. Can the LHC change this? Yes, and we will have to wait and see.Even so, I claim that the structure of theories is such that we only achieve partial unifications, incomplete and dependent on parameters. Instead of insisting on "beauty" as a final theory, we should be thinking of beauty as based on what we have, including the asymmetries that make matter and life possible. It's about a new aesthetics where there is no equating beauty with symmetry.

Marcelo Gleiser wrote:Steve Colyer wrote: "There is nothing behind our ignorance except ignorance itself. Ignorance itself is defined as things we do not know, therefore I am calling you out on being tautological."

I'm not sure I get this. It's not a game with words, it's about what people think it's "out there". There's no tautology at all!

The context was my comment to the following comment by yours which ended the article above, to whit:

Marcelo Gleiser wrote (and ends his above article with):Let me make my position clear: behind our ignorance there is only the science we still don’t know.

Then yes, in that sense, it's a tautology. If you want to get weenie about it, then go ahead and weenie semantically party on, Garth, I mean Dr. Gleiser.

I think my POINT was you could have ended your defense of your metaphysics much better, and that maybe you should redo that last sentence to make more sense, is all I'm saying.

The MOST important point though is that you are correct in that science seen as a religion is simply wrong, which I agree with.

And ALSO on point, that is to be perfectly honest, I applaud that you ask us to consider at least the possibility that there very may well be no TOE. (I'll see your no-TOE, and raise it a no-QG and no-GUT. Call or fold?)

But that's what Philosophers are for, as my/our friend George Musser says: to question the assumptions. That's their job.

Are you a philosopher?

Are you a current or former superstrings theorist? Like Number Theory much? Me too. But...

... we live in a fractal universe. Therefore please advise how "dimensions" are integer-based, if so. I'm all ears.

Although the question of existence of a TOE seems to reduce to a personal belief, Goedel's theorems from mathematical logic imply that a TOE cannot exist. Essentially, a TOE has to be a mathematical theory which contains arithmetic, and as such, according to the Goedel theorem, it will contain undecidable statements. These are the statements which cannot be proved or disproved from the postulates, and such a statement can be taken to be true and joined to the set of postulates. Hence one can never have a simple TOE, i.e. one with finitely many postulates or equations, which can describe everything. The best one can do is to find a minimal theory which describes a given set of phenomena.

/*...you don't have any theory just a random and incoherent mix of words and ideas...*/Try to be more specific. Which ideas are incoherent in your opinion, for example? Isn't your post just another way, in which ignorant community refuses any idea leading to TOE? Prove it.

The proof of logical inconsistency isn't so free league, as you probably believe. If it wouldn't, we couldn't distinguish logically inconsistent theories from those logical ones.

Again, any discussion of TOE is a bit moot in my opinion as the questions of GUT and QG are more immediate. We'll probably never have a TOE without finding the answers to GUT and QG, with an outside chance that finding a TOE with only one of them.

In other words, it seems to me we're getting a bit ahead of ourselves here. So the better question(s) may be "does a GUT exist?" and "does a theory of quantum gravity exist?"

OK, time for our daily Feynman quote:

"If our small minds, for some convenience, divide this glass of wine, this universe, into parts - physics, biology, geology, astronomy, psychology, and so on - remember that Nature does not know it!" ... Richard Feynman

I can appreciate what you are saying that ultimate understanding has to be taken in the context as to how it is able to be arrived at. What I`m more concerned with is what stands as being the core elements within science`s philosophy, with having as its first premise or axiom if you like, being that reality is a construct that is reasonable.

That is I`ve found that since the advent of what I would call the quantum era that physics has diminished or totally given this up as its most basic assumption, with resultantly having many permitting and with some insisting as alternatives multiple or worse endless prescriptions for having a reality; not resultant of being reasonable, but rather the consequence of things perceived in an opposite manner.

I would therefore contend that beginning with this surrender of the philosophy`s core principles has both mitigated and allowed for the erosion of science, to the point as me finding many as yourself too pessimistic by failing to maintain science`s singular goal and promise, which is to facilitate an ever increasing and perhaps final understanding of reality; that is whether it necessarily has a why within it or not.

We don't have any a priori notion of why "reality" should be like this or otherwise. For deep logical reason I've noted before, I don't see how we can. There is nothing in logical analysis that can "bless" some mathematical constructs with a "right to life" over others - ie, to be incarnate in the special manner we feel that we are. To be, as Madonna put it, "living in a material world." (I like to say, it's like number 23 specially existing also as brass numerals "just because", despite being just another number ...)

Many thinkers cogently argue we can't even make that distinction. I think that collides with our basic feeling of being alive etc. but it is near impregnable as a strict logical critique of material realism being coherently distinct from abstractly descriptive and totally unselective modal realism.

Hence some believe in MUH: that all structures in the Platonic mindscape exist (logically wide-open, a far bigger set than even the wildest string-theory landscape etc.) If so there is little point in looking for a fundamental theory that makes sense or is beautiful etc, because we are just in a possible world that allows us to exist.

However, that presents deep Bayesian expectation problems. If that were true, our greatest expectation would be living in a universe just orderly enough to get us in this condition and to this point, and no more so (because there are so many more ways to do that than to be very neatly consistent, with identical electrons and laws that don't change over time etc. in various odd ways.)

So no one knows what's going on or why it should. Find a TOE that works if you want, but be aware of the logical problem of justifying it existentially.

Nicely put Neil. So are you going to buy the book? $13.16 on Amazon today, that's pretty cheap for a hardcover, hmm.

I think I'll buy it, because Dr. Gleiser is known as "The Brazilian Carl Sagan" according to one review (5 5-stars, 1 4-star so far) at the Amazon page for the book. Lord knows I loved Carl, the big adorable Atheist pothead was nevertheless passionate in a positive way, and also because I expect good things from Brazil in this century, so that's good enough for me for the time being. We'll see.

For everyone who is still believing in the innocense of mainstream physics maybe the following excert from the retirement address of the president of APS Prof. Dr. Robert Willson, which appeared in Physics Today in 1984.

"Unification is becoming almost serious enough that it bears a bit of watching--- from a strictly occupational point of view. I suppose thausands of physicists, perhaps all, secretly fantasize stumbling upon the ultimate theory of everything. This is not completely unreasonable, for it is almost a religious precept of sceince that the solution to a problem is most likely to come by indirection.

Just suppose, even though it is probably a logical impossibility, that some smart aleck came up with a simple self-evident, closed theory of everything. I---and so many others---have had a perfectly wonderful life pursuing the will-o'-the-wisp of unification. I have dreamed of my children, their children and their children's children all having this same beautiful experience.

All that would end.

APS membership would drop precipitously. Fellow members, could we afford this catastrophe? We must prepare a crisis-management plan for this eventuality, however remote. First we must voice a hearty denial. Then we should ostracize the culprit and hold up for years any publication by the use of our well-practiced referees. Just to be safe, we should put the paper on our Index---I mean in our index--- where it can be lost for centuries... "

To make things perfectly clear, with full respect & occasional personal sympathy to our little Bee - she fits the ignorant approach of mainstream quite perfectly, too. I can see any difference, here.

What she is really interested for is just a traveling from flower to flower, from city to city, from university to university, from conference to conference. I can imagine, she can imagine to spent whole her life in such way with absolutelly no problem. She just poses an averaged picture of contemporary generation of young physicists.

Yes, Pmer he did, at least according to Wikipedia entry on Carl Sagan:

Sagan was a user and advocate of marijuana. Under the pseudonym "Mr. X", he contributed an essay about smoking cannabis to the 1971 book Marihuana Reconsidered.[43][44] The essay explained that marijuana use had helped to inspire some of Sagan's works and enhance sensual and intellectual experiences. After Sagan's death, his friend Lester Grinspoon disclosed this information to Sagan's biographer, Keay Davidson. The publishing of the biography, Carl Sagan: A Life, in 1999 brought media attention to this aspect of Sagan's life.

However, that's Wiki. I am increasingly doubting the veracity of the facts there, but I can believe that about Carl. He was always smiling. What were we talking about again? Whoa. ;-)

I prefer this bit from the same article:

Isaac Asimov described Sagan as one of only two people he ever met whose intellect surpassed his own. The other, he claimed, was the computer scientist and artificial intelligence expert Marvin Minsky.

Zephir, jet setting around the globe isn't as glamorous as you seem to imply. There's airports for example, ugh.

Also, while getting the finest minds in a narrow and specific cutting-edge field together via technology will only get easier over time, putting them physically together for week-long workshops reaps loads more benefits, which justifies the expense.

I think "driccardi" is right. He is talking about Metaphysics as the ultimate scientific explanation of the Physics. To him it seems that some scientist have fear of breaking a taboo and leave the monopoly of the metaphyisical explanations to the religions. He expressed his hope that this will change soon.

Actually metaphysics is the only "physical" discipline which deals with a foundation that is truly fundamental. If we were able to conduct metaphysics in a scientific way we would indeed get key insights how a final theory about the Universe has to look like.But in the last two thousand years no way was found how to deal with a branch that is of transcendent character. This was and is still the main problem of metaphysics..And just this problem can be solved, because the property of transcendence resp. of invisibility is a highly restrictive condition with respect to the visible universe. It gives rise to a kind of radical non-dual conception. There are in fact some empirical data which are confirming the existence of such conception.

Further information you can get at:

http://www.fqxi.org/community/forum/topic/502

If this conception would truly be there, then a piece of a final theory of the Universe is catched.